Banging wheels
Discussion
My old mk1 SEAT Leon Cupra R did this, when it was still totally stock and on Falken tyres. Upgraded to Vredestein Ultrac Sessantas and it stopped completely. Didn't even come back after I'd had it remapped and had an upgraded turbo, intake, intercooler etc fitted and taken it to nearly 300bhp. The cause is a combination of stiff suspension and poor tyres, better tyres should sort it out.
dhutch said:
Mr Tidy said:
I think it's a FWD problem to be honest!
Not all fwd. My pug 306 (soft sprung and high profile tyres) and host of other cars I've been in would break traction quite carmly. Daniel
The RWD Alfa's of the day were the opposite. Decent location and lo unsprung weight, yes, but also relatively soft, long travel springs and expensive dampers - Konis' Bilsteins, etc.
One of my 200 SX's did it - much to my irritation - as I modded it and was advised to use certain springs and dampers and it ended up over sprung/under damped
My wife's Clio does it but dampers cost about 50p.
My povvo-fleet-spec Cavalier did it but the CDX one didn't (but it had SRI suspension with Bilsteins).
The dampers on my previous E Class became a bit tired and it would do it if I really gave it the beans at low speed on a greasy corner.
The current one is far newer and there's not a hint of it.
dhutch said:
You can try it as a test but I wouldn't drive it like that.
Why not, 32/30 isent that low to be honest so wouldent be dangerous.dhutch said:
OP, what's the car? Age? Mileage? Lowered? Dampers?
As said, it's what was called axle tramp imo. MOT should show worn bushes but might not, even less good at showing worn dampers.
Daniel
As said, it's what was called axle tramp imo. MOT should show worn bushes but might not, even less good at showing worn dampers.
Daniel
Its a fiesta mk7 st.
3 years old.
30,000 miles on clock.
Lowered on eibach springs (common upgrade)
Shocks never changed but are fine with the above springs.
Shiv_P said:
My Focus ST does this as well. At first I thought it was ESP so turned it off but still did it so I assume at 105k miles it probably needs a damper refresh 
Mine's done it since the day I bought it and it's on 40k now so nothing to do with worn suspension components. It's just what they do.dieseluser07 said:
Lowered on eibach springs (common upgrade)
Shocks never changed but are fine with the above springs.
But are they fine? I fitted Eibach springs to my 200SX and they were both lowered and uprated. And the dampers couldn't cope.Shocks never changed but are fine with the above springs.
When springs are uprated it will be always harder for the dampers to control the oscillations.
BTW some people call dampers "shock absorbers" but it's the springs that actually absorb the shocks. The dampers are there to dampen down the movement of the springs. If you've ever followed an old shagged car with shot dampers you'll have seen the rear wheels bouncing up and down with high frequency. That's what a spring will naturally do when there is no damping at all.
Some people say it can't be down to the dampers as their car has done it from new. I just say the accountants spend more money on things that people can see (touch screens, bling rims, privacy glass) and less on things they can't (dampers).
Back in the day when I mucking about with Alfa's I never bothered "uprating" the springs. I got much better results but spending my money on decent dampers.
dieseluser07 said:
Why not, 32/30 isent that low to be honest so wouldent be dangerous.
Its a fiesta mk7 st.
3 years old.
30,000 miles on clock.
Lowered on eibach springs (common upgrade)
Shocks never changed but are fine with the above springs.
I am not saying it would be dangerous, and if your on track and testing tyre temps etc then fine, but if its in the book at 36 then intentionally dropping nearly 20% to 30 for daily road use isnt exactly advisable. Its a fiesta mk7 st.
3 years old.
30,000 miles on clock.
Lowered on eibach springs (common upgrade)
Shocks never changed but are fine with the above springs.
Did the car do it before the eibachs?
My 330ci is on eibachs with bilstine B4's and while im aiming for a oem ride and setup are unintentionally a bit lower, again its common thing to do in part because there the BMW springs are mad money and the pattern part market for the sport variant of what is now a 17yo car is limited.
However just because it's common doesn't mean it in any way designed or engineered that way.
At 3 years and 30k the origanal dampers should be working about how they left the factor, but having fitted shorter stiffer springs are likely now under damped.
Daniel
dhutch said:
AC43 said:
No, not just a FWD problem.
Oh indeed, if anything I would expect its worse on an under-damped rwd. Suspension geometry likely effect it too, meaning some cars will be more prone than others.Daniel
Out of interest I hired a 500X in Italy in August. Dents in every panel, interior hanging off, 50k+ miles but the suspension & brakes were spot on.
They'd resisted the urge to fit rock hard springs (to contain the high CoG) and cheapo dampers (because they could) and the result was surprisingly good. Decent bump absorbtion, decent ride, good high speed stability, no axle tramp.
Compared to the comedy bouncy castle act I'd experienced the same year in an XC40 and Pug 2008 it was night and day.
It's good to see some companies paying attention to chassis engineers.
Weren't you the guy who said you didn't like having a common car, because chavs drive them badly?
Tyre pressures are relative, 32 psi can be high or low depending on the car, and can have a drastic effect on tyre life/performance. Running lower than recommended pressures will increase shoulder wear, too much will increase center wear etc. but ultimately, if that fixes it, you're masking the symptoms (and causing another issue) rather than fixing the problem.
Watch this video, as it gives a relatively decent example of wheel hop/tramping in a rwd car, so you can understand the forces that are exerted on driven wheels.
Do you know the spring rate of the eibachs? Is it the same as the original springs or higher? If the spring rate is higher, your damper is doing less work on compression (upward motion of the wheel) as your springs are stiffer (so resisting more upwards motion), and then doing more work trying to slow the rebound (downward motion of the wheel) as your springs may well be overpowering them.
Tyre pressures are relative, 32 psi can be high or low depending on the car, and can have a drastic effect on tyre life/performance. Running lower than recommended pressures will increase shoulder wear, too much will increase center wear etc. but ultimately, if that fixes it, you're masking the symptoms (and causing another issue) rather than fixing the problem.
Watch this video, as it gives a relatively decent example of wheel hop/tramping in a rwd car, so you can understand the forces that are exerted on driven wheels.
Do you know the spring rate of the eibachs? Is it the same as the original springs or higher? If the spring rate is higher, your damper is doing less work on compression (upward motion of the wheel) as your springs are stiffer (so resisting more upwards motion), and then doing more work trying to slow the rebound (downward motion of the wheel) as your springs may well be overpowering them.
AC43 said:
dieseluser07 said:
Lowered on eibach springs (common upgrade)
Shocks never changed but are fine with the above springs.
But are they fine? I fitted Eibach springs to my 200SX and they were both lowered and uprated. And the dampers couldn't cope.Shocks never changed but are fine with the above springs.
When springs are uprated it will be always harder for the dampers to control the oscillations.
BTW some people call dampers "shock absorbers" but it's the springs that actually absorb the shocks. The dampers are there to dampen down the movement of the springs. If you've ever followed an old shagged car with shot dampers you'll have seen the rear wheels bouncing up and down with high frequency. That's what a spring will naturally do when there is no damping at all.
Some people say it can't be down to the dampers as their car has done it from new. I just say the accountants spend more money on things that people can see (touch screens, bling rims, privacy glass) and less on things they can't (dampers).
Back in the day when I mucking about with Alfa's I never bothered "uprating" the springs. I got much better results but spending my money on decent dampers.
It's my understanding that this noise is not wheels or suspension, it is the engine management doing something on purpose (controlled retardation maybe) in order to control the power while simultaneously telling you to back off the mic a bit.
My Golf GTI did it from brand new, as did a hired GTD I had.
I believe (I'm prepared to be proved wrong here) that it can be altered in software by changing the torque values at which it occurs.
My Golf GTI did it from brand new, as did a hired GTD I had.
I believe (I'm prepared to be proved wrong here) that it can be altered in software by changing the torque values at which it occurs.
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